Method of mining single steeply-inclined thick coal seam

ABSTRACT

Provided is a method of mining a single steeply-inclined thick coal seam, which belongs to the mining engineering field. The mining method includes: carrying out one transport crossheading along a floor of the coal seam to constitute a production system together with rises on both sides of a district; arranging a top-coal caving hydraulic support along a thickness of the coal seam in the transport crossheading, with a cyclic advance interval being 1.0 m; maintaining one section of return air channel close to a side of a roof that is in a gob and behind the hydraulic support. In a case of mining, caved coals fall on a scraper conveyer and transported through a belt conveyer. Fresh air flow required for a working surface enters the transport crossheading through a district transport crosscut and a track rise, and then enters the return air rise through the return air channel after washing the working surface. A unique return air channel is adopted. The method features advantages such as simple roadway arrangement system, strong adaptability, large yield of working surface, and high safety level.

TECHNICAL FIELD

The present disclosure relates to the field of coal mining technologyand in particular to a method of mining a single steeply-inclined thickcoal seam

BACKGROUND

A method of mining steeply-inclined thick coal seam always is adifficult problem in the mining technology field and already drawsattention of relevant state authorities. Steeply-inclined thick coalseams in China are mostly distributed in small and medium-sized mines.Geological conditions of the coal seams are complex and the coal seamsare difficult to mine. Some mines have features such as many faults,less reserves, high content of gas and bad storage conditions. Becausethe steeply-inclined coal seam is special, there are many problems withmining, for example, a loss ratio of coals is up to 40-50% and a gangueratio of the coals is generally below standard; an drivage ratio ofroadway is high, and the drivage ratio of roadway affects the expensesof roadway drivage and maintenance, affects handover of working surfacesof a mining zone and even bring an impact to ventilation of miningshafts; ventilation conditions are bad, ventilation conditions of thesteeply-inclined coal seam are very complex; labor intensity of workersis high, mining personnel often encounters problems such as a largeslope of working surface, small space, falling coals during mining, anddifficulties in supporting, transporting materials and walking during amining process due to limitation of complex mining conditions of thesteeply inclined coal seam; mining benefit is bad, and compared withinclined or nearly horizontal coal seams, the steeply inclined coal seamhas disadvantages such as high costs, bad quality, high miningdifficulty level, small scale, and low benefits. Therefore, research onthe method of mining a steeply inclined thick coal seam still hassignificant impact on the development of Chinese coal industry.

SUMMARY

The object of the present disclosure is to provide a method of top coalcaving for mining a single steeply-inclined thick coal seam. A roadwayis arranged simply, a drivage ratio of the roadway is reduced, and amining working surface adopts mechanized production to facilitateoperation and transportation. With a unique return air channel,ventilation is very convenient.

A technical problem to be solved by the present disclosure to completethe above task is that: how to complete advanced temporary supporting ofa coal mining working surface, and keep the working surface normallyventilated to maintain a return air channel on a precondition ofensuring normal mining of the working surface.

To solve the above technical problem, the following technical solutionis adopted in the present disclosure.

A system for mining a single steeply-inclined thick coal seam includes aroadway arrangement system, a supporting system, a transportation systemand a ventilation system. The roadway arrangement system is formed by atransport crossheading and a district rise, the transport crossheadingis arranged on a floor of the thick coal seam and the district rise isobtained by connecting two sides of the coal seam.

The supporting system includes a top-coal caving hydraulic support, asingle hydraulic support, a hinged top beam, an anchor bolt and a metalnet. The top-coal caving hydraulic support is located in the transportcrossheading, a roof in the roadway is supported by disposing an anchorbolt with protection provided by a disposed metal net, and advancedtemporary supporting is completed in cooperation with the singlehydraulic support and the hinged top beam located in front of a workingsurface.

The transportation system includes a scraper conveyer and a beltconveyer. A head of the scraper conveyer is overlapped with a tail ofthe belt conveyer.

The ventilation system includes a return air channel. The return airchannel is close to a coal seam roof side that is behind the top coalcaving hydraulic support and in a gob. The return air channel is used toallow dirty air washing the working surface to enter a return air risein the district rise.

For the above return air channel, one herringbone return air channel ismaintained by I steel at a side of the gob behind the top coal cavinghydraulic support.

As a preferred solution of the present disclosure, the transportcrossheading adopts a quadrilateral roadway.

As another preferred solution of the present disclosure, a cyclicadvance interval of the top-coal caving hydraulic support is 1.0 m.

Further, there is only one transport crossheading in the roadwayarrangement system.

Another object of the present disclosure is to provide a method of atop-coal caving for mining a single steeply-inclined thick coal seam.

The method of mining a single steeply-inclined thick coal seam includesthe following steps in sequence.

a. The transport crossheading is carried out along a floor of a coalseam to connect the district rises on both sides of the coal seam.

b. The top-coal caving hydraulic support is arranged along a coal seamthickness within the transport crossheading, and each cyclic advanceinterval of the top-coal caving hydraulic support is 1.0 m.

c. One section of return air channel is maintained at a side of the gobof the top-coal caving hydraulic support; a next section of return airchannel is maintained with advance of the top-coal caving hydraulicsupport to lead to a district return air rise and so on.

d. The working surface is advanced by adopting full seam mining of topcoal caving and the caved coals are transported out by thetransportation system.

e. Fresh air flow arrives at a track rise through a district transportcrosscut and then enters the transport crossheading and then to themining working surface. The dirty air washing the working surfacearrives at the district return air rise through the return air channeland then enters a mining shaft return air system.

The mining method is applicable to mining of a single steeply-inclinedthick coal seam of more than 5.5 m.

The above technical solution has the following difficult points: to keepthe mining working surface normally ventilated, it is required tomaintain one section of return air channel before caving of the gob; anda proper advance interval of the top-coal caving hydraulic support isdetermined to ensure a high coal recovery ratio, a low gangue ratio anda high caving efficiency.

Preferably, at step d, the caved coals fall on the scraper conveyer andscattered coals are loaded onto the scraper conveyer and then coals aretransported out in cooperation with the belt conveyer.

The beneficial technical effects of the present disclosure are describedbelow.

The mining method of the present disclosure improves production capacityof the working surface and reduce the drivage ratio of the roadway andmay be applied to mine a single thick coal seam of more than 5.5 m,where the transport crossheading and two rises constitute ventilation,thereby avoiding the problems of ventilation and gas accumulation at thetime of top coal caving and improving the environment of the workingsurface.

The method of present disclosure is characterized as follows:

(1) According to the method of top coal caving for mining a singlesteeply inclined thick coal seam of the present disclosure,characteristics such as a large dip angle of coal seam and a small roofpressure are fully utilized to form a complete production system. Inthis way, the problems that coals and gangues mined from asteeply-inclined coal seam according to a conventional method roll alongthe floor to easily harm persons and knock down supports and so on aresolved, thereby realizing high yield and high efficiency of mining thesteeply-inclined coal seam.

(2) Another feature of the present disclosure is to maintain one returnair channel by I steel within the gob, so that the transportation andventilation of coals can be completed with only one transportcrossheading. Along with advance of the top-coal caving support, thereturn air channel is maintained behind the working surface so thatfresh air flow enters the working surface, and the dirty air washing theworking surface enters the return air rise through maintained return airchannel, thereby forming a complete ventilation system.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of a working surface of a mining method accordingto an example of the present disclosure.

FIG. 2 is a top view of a working surface arrangement according to anexample of the present disclosure.

FIG. 3 is a top view of a district rise arrangement manner according toan example of the present disclosure.

In the drawings, 1 refers to a coal seam, 2 refers to a transportcrossheading, 3 refers to a top-coal caving hydraulic support, 4 refersto a return air channel, 5 refers to I steel, 6 refers to a scraperconveyer, 7 refers to a belt conveyer, 8 refers to a gob, 9 refers to areturn air rise, 10 refers to a track rise, 11 refers to a transportrise.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The present disclosure provides a method of mining a singlesteeply-inclined thick coal seam. To describe the advantages andtechnical solutions of the present disclosure more clearly, the presentdisclosure will be detailed below in combination with specific examples.

As shown in FIGS. 1, 2, and 3, there is provided a system for mining asingle steeply-inclined thick coal seam, including a roadway arrangementsystem, a supporting system, a transportation and a ventilation system.The roadway arrangement system is formed by a transport crossheading 2,a return air rise 9, a track rise 10, and a transport rise 11. Thetransport crossheading 2 is arranged at the roof of the thick coal seam,and the return air rise 9, the track rise 10 and the transport rise 11are obtained by connecting both sides of the coal seam. The supportingsystem includes a top-coal caving hydraulic support, a single hydraulicsupport and a hinged top beam. The top coal caving hydraulic support isarranged at the position of the top coal caving hydraulic support shownin FIG. 2 and is located within the transport crossheading and furtherarranged along the thickness of the coal seam. The transportation systemincludes a scraper conveyer 6 and a belt conveyer 7. A head of thescraper conveyer 6 is overlapped with a tail of the belt conveyer 7. Theventilation system includes a return air channel 4 and a I steel 5. Thereturn air channel is maintained by the I steel at the side of the gobbehind the top-coal caving hydraulic support and used to allow the dirtyair washing the working surface to enter the return air rise in thedistrict rise.

Example 1

Descriptions are made with a mine A mining shaft 2 coal seam as anexample.

The basic conditions are as follows: 2 coal seam is mined in the miningshaft, the coal seam is 5.8 m thick, an dip angle of the coal seam is 55degrees, and the lithology of the roof and the floor is relativelystable siltstone and fine sand stone.

The coals are mined by the above mining method.

The transport crossheading is carried out by adopting a quadrilateralroadway along a floor of the coal seam 1. The top-coal caving hydraulicsupport 3 is arranged in the coal seam 1, the scraper conveyer 6 isplaced along a strike between supports in the transport crossheading ofthe coal seam 1 and the belt conveyer 7 is installed at a properposition in the transport crossheading. The head of the scraper conveyer6 is overlapped with the tail of the belt conveyer 7 to form a raw coaltransportation of the working surface. Each cyclic advance interval ofthe supports of the working surface is 1.0 m. The working surface isadvanced by natural caving of coal seam and then low-position caving ofthe top coal. The advance supporting of the working surface is performedby supporting with an anchor bolt and a metal net in cooperation withsupporting of the single hydraulic support and the hinged top beam. Whenone cyclic advance interval is reached, fixing is performed with fixedpiles so that the support forward-pushing cylinder is connected with thefixed pile to advance the supports alternately one by one, and then anext section of return air channel is maintained into the gob 8 behindthe support by I steel 5 at the side of the transport crossheading. In acase of top coal caving, the coals falling from a caving opening slideto the scraper conveyer through a special chute and the scattered coalsare shoveled to the scraper conveyer by hand for transportation.

As shown in FIGS. 1, 2 and 3, the ventilation path is described asfollows: fresh air flow enters the transport crossheading of the coalseam 1 through the track rise 10 and gets to the mining working surfaceand then the dirty air arrives at the district return air rise 9 throughthe previously maintained return air channel 4 and then enters themining shaft return air system through the district return air crosscut.

The present disclosure has the following advantages:

Firstly, the drivage ratio of the roadway is low, and there is only onetransport crossheading. In this case, maintenance expenses of theroadway drivage are reduced.

Secondly, the yield of the working surface is large and the coal loss issmall.

Thirdly, the working surface is arranged simply with high adaptabilityand is applicable to mining of a steeply-inclined thick coal seam ofmore than 5.5 m.

Fourthly, for mining of top coal caving, a professional top coal cavinghydraulic support is used in cooperation with low position top coalcaving. The operation is simple and fewer workers are needed. Forexample, 4-5 persons are needed for each shift.

Fifthly, a unique return air channel is adopted to solve the problems ofbad ventilation conditions and gas accumulations on the working surface,thereby improving safety of the working surface and the workingenvironment of the workers.

Parts not mentioned in the present disclosure may be implemented byusing the prior art.

Although many terms such as the belt conveyer and the hydraulic supportsare used in the present disclosure, the possibility of using other termsis not precluded. Those simple substitutions made by those skilled inthe art for these terms according to the teachings of the presentdisclosure shall all fall within the scope of protection of the presentdisclosure.

1. A system for mining a single steeply inclined thick coal seam,comprising a roadway arrangement system, a supporting system, atransportation system and a ventilation system, wherein, the roadwayarrangement system is formed by a transport crossheading and a districtrise, the transport crossheading is arranged at a floor of the thickcoal seam and the district rise is obtained by connecting both sides ofthe coal seam; the supporting system comprises a top-coal cavinghydraulic support, a single hydraulic support, a hinged top beam, ananchor bolt and a metal net, the top-coal caving hydraulic support islocated in the transport crossheading, a roof in the roadway issupported by disposing an anchor bolt with protection provided by adisposed metal net, and advanced temporary supporting is completed incooperation with the single hydraulic support and the hinged top beamlocated in front of a working surface; the transportation systemcomprises a scraper conveyer and a belt conveyer, and a head of thescraper conveyer is overlapped with a tail of the belt conveyer; and theventilation system comprises a return air channel, the return airchannel is close to a coal seam roof side that is behind the top coalcaving hydraulic support and in a gob, the return air channel is used toallow dirty air washing the working surface to enter a return air risein the district rise.
 2. The system for mining a single steeply-inclinedthick coal seam according to claim 1, wherein the transport crossheadingadopts a quadrilateral roadway.
 3. The system for mining a singlesteeply-inclined thick coal seam according to claim 1, wherein a cyclicadvance interval of the top coal caving hydraulic support is 1.0 m. 4.The system for mining a single steeply-inclined thick coal seamaccording to claim 1, wherein there is only one transport crossheadingin the roadway arrangement system.
 5. A method of mining a singlesteeply-inclined thick coal seam, comprising in sequence: a. carryingout a transport crossheading along a floor of the coal seam to connectdistrict rises on both sides of the coal seam; b. arranging a top coalcaving hydraulic support in the transport crossheading along a thicknessof the coal seam, each cyclic advance interval of the top coal cavinghydraulic support being 1.0 m; c. maintaining one section of return airchannel at a side of a gob of the top coal caving hydraulic support, andmaintaining a next section of return air channel along with advance ofthe top coal caving hydraulic support to lead to a district return airrise and so on; d. advancing the working surface by full seam mining oftop coal caving and transporting out the caved coals by a transportationsystem; e. fresh air flow arriving at a track rise through a districttransport crosscut and then entering the transport crossheading and thento the mining working surface, and dirty air washing the working surfacearriving at the district return air rise through the return air channeland then entering a mining shaft return air system; wherein the miningmethod is applicable to mining of a single steeply-inclined thick coalseam of more than 5.5 m.
 6. The method of mining a singlesteeply-inclined thick coal seam according to claim 5, wherein, at stepd, the caved coals fall on the scraper conveyer and scattered coals areloaded onto the scraper conveyer and then the coals are transported outin cooperation with the belt conveyer.